This invention relates to insecticidal compositions; more specifically, the stabilization of N-aminosulfenyl derivatives of carbofuran by adding an epoxide compound thereto.
U.S. 4,006,231 discloses insecticidal (methyl) (aminosulfenyl)carbamic acid esters of 2,3-dihydro-2,2-dimethyl-7-benzofuranol, as well as formulated insecticidal compositions containing such carbamates in admixture with a carrier. The common name for 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methyl carbamate is carbofuran, and the N-aminosulfenyl derivatives of carbofuran are of commercial interest, because they exhibit lower mammalian toxicity than the parent carbofuran.
Investigation of the N-aminosulfenyl derivatives of carbofuran directed toward their commercialization has shown that both the technical grade derivatives and formulations thereof undergo decomposition, giving the materials an unacceptably short shelf life. It is known that one of the decomposition products is carbofuran. It has been reported that the N-S bond in N-sulfenylated derivatives of carbofuran is labile [Chiu, et al., Pestic. Biochem. Physiol., 5, 359 (1975)].
It is fairly common that a pesticide exhibits a shorter than desired shelf life. Various antioxidants, inhibitors, and scavengers have been developed over the years for addition to pesticidal compositions to stabilize them against spontaneous decomposition. As a rule, different classes of compounds require different stabilizers, because the mechanisms of decomposition vary from one pesticide class to the next.
It is known in the art to stabilize organophosphate insecticides against decomposition by adding an epoxide compound to the formulated material [see, for example, U.S. Pat. No. 3,867,526]. Epoxide compounds are also known to stabilize formulations of the chlorinated hydrocarbon pesticide, endosulfan [see, for example, U.S. Pat. No. 3,952,102].